Assertion (A): van der Waals' forces are reponsible for chemisorptions.

Reason (R): High temperature is favourable for chemisorptions.

The correct answer is:

• (A) is false, but (R) is true

• Both (A) and (R) are correct and (R) is the correct explanation of A

• Both (A) and (R) are correct and (R) is not the correct explanation of (A)

• (A) is true, but (R) is false

What are the shapes of ethyne and methane?

• Square planar and linear

• Tetrahedral and trigonal planar

• Linear and tetrahedral

• Trigonal planar and linear

In an atom the order of increasing energy of electrons with quantum numbers

(i) n=4, l=1      (ii) n=4, l=0     (iii) n=3, l=2 and (iv) n=3, l=1 is

• III < I <IV < II

• II < IV < I<III

• I <III <II <IV

• IV< II <III <I

The number of angular and radial nodes of 4d orbital respectively are

• 3,1

• 1,2

• 3,0

• 2,1

The number of electrons is the valence shell of the central atom of a molecules is 8. The molecule is

• BCl₃

• BeH₂

• SCl₂

• SF₆

Which one of the following has longest covalent bond distance?

• C—C

• C—H

• C—N

• C—O

The ratio of rates of diffusion of gases X and Y is 1 : 5 and that of Y and Z is 1 : 6. The ratio of rates of diffusion of Z and X is

• 1:30

• 1:6

• 30:1

• 6:1

8.

KMnO₄ reacts with KI in basic medium to form I₂ and MnO₂. When 250ml of 0.1M KI solution is mixed with 250ml of 0.02M KMnO₄ in basic medium, what is the number of moles of I₂ formed?

• 0.015

• 0.0075

• 0.005

• 0.01

The oxide of a metal contains 40% of oxygen. The valency of metal is 2. What is the atomic weight of metal?

• 24

• 13

• 40

• 36

The temperature of K at which ΔG = 0, for a given reaction with ΔH =- 20.5 kJ mol^-1 and ΔS=-500 JK^-1mol^-1 is

• -410

• 410

• -2.44

• 2.44